1. Field of the Invention
The present invention relates to pipe lining techniques, and more particularly to a method of inspecting a pipe liner bag.
2. Description of the Related Art
When an underground pipe, such as pipelines and passageways, becomes defective or too old to perform properly, the pipe is repaired and rehabilitated without digging the earth to expose the pipe and disassembling the sections of the pipe. This non-digging method of repairing an underground pipe has been known and practiced commonly in the field of civil engineering. Typically, the method is disclosed by Japanese Provisional Patent Publication (Kokai) No. 60-242038.
According to the method described in the above-mentioned publication, the pipe repair method comprises inserting a sufficiently long tubular flexible liner bag into the pipe to be repaired by means of a pressurized fluid, like air and water. The tubular liner bag is made of a flexible resin-absorbent material impregnated with a thermosetting resin, and has the outer surface covered with an impermeable plastic film.
More particularly, according to the publication, the tubular flexible liner bag is closed at one end and open at the other; the tubular flexible liner bag is first flattened, then, the closed end of the tubular liner bag is tied to a control rope; the open end of the tubular liner bag is made to gape wide and hooked (anchored) at the end of the defective or old pipe in a manner such that the wide-opened end of the liner completely and fixedly covers and closes the pipe end; a portion of the liner is pushed into the pipe; then, the pressurized fluid is applied to the portion of the tubular liner such that the fluid urges the tubular liner to enter the pipe. Since one end of the tubular liner is hooked at the end of the pipe, it remains there while the rest of the flexible liner bag is turned inside out as it proceeds deeper in the pipe. (Hereinafter, this manner of procedure shall be called "everting".) When the entire length of the tubular liner bag is everted (i.e., turned inside out) into the pipe, the control rope holds the closed end of the tubular liner bag to thereby control the length of the tubular liner in the pipe. Then, the everted tubular liner is pressed against the inner wall of the pipe by the pressurized fluid, and the tubular flexible liner is hardened as the thermosetting resin impregnated in the liner is heated, which is effected by heating the fluid filling the tubular liner bag by means of a hot steam, etc. It is thus possible to line the inside wall of the defective or old pipe with a rigid liner without digging the ground and disassembling the pipe sections.
After the pipe has been lined by the method mentioned above, it is necessary to inspect how the lined material is hardened and whether an air-tight sealing effect is sufficient or not. Conventionally, the inspection for hardened lining material has been carried out by a self-running TV camera or the like which is introduced into a pipe liner bag to monitor a hardened state of the pipe liner bag on the repaired inner wall of the pipeline. Also, for inspecting the air-tight condition, the pipe liner bag is filled with water which is held therein for a predetermined time period, such that an amount of water decreased during that time period is detected to determined whether the air-tight sealing effect is sufficiently provided.
However, the conventional method using a self-running TV camera or the like for inspecting a hardened condition allows only the inner wall lined with the lining material of the pipeline to be inspected but cannot accurately determine whether or not the lining material on the inner wall of the pipeline has been completely hardened.
Also, the method of filling a pipe liner bag with water for inspecting an air-tight condition has drawbacks in that the provision of a large amount of water is difficult, and this inspection requires a lot of facilities, operators and steps.
Further, conventionally, the above two inspections for the hardened condition of the lining material and for the air-tight condition are made in separate procedures so that these inspections require a lot of labor and time.